NO, 12 STRONG AND HERTLEIN : MARINE MOLLUSKS 241 



rounded, smooth except for fine lines of growth and, on the first whorl, 

 faint indications of spiral striations, sutures appressed; periphery of last 

 whorl marked by a rounded spiral cord; base rounded, marked by 3 

 spiral cords, the first about as strong as the peripheral cord and sepa- 

 rated from it by a groove about as wide as the cords; the second and 

 third cords are about equally spaced but are much more slender, these 

 cords followed by a wider smooth space extending to the edge of the 

 wide, open umbilicus, on the walls of which there are 8 strong, toothlike 

 axial folds; aperture nearly circular, the posterior angle falling just 

 above the peripheral keel, outer lip thickened ; inner lip short, straight, 

 with a thick callus over the body of the shell. The type measures: 

 greater diameter, 1.4 mm; height, 0.5 mm. 



Holotype: No. 713 (Calif. Acad. Sci. Paleo. Type Coll.), from 

 Loc. 27,229 (C.A.S.), dredged in from 3 to 9 fms. in Bahia Honda, 

 Panama. L. G. Hertlein collector. Nine additional specimens were 

 dredged at the same locality. 



Similar strong axial ribs on the walls of the umbilicus is the char- 

 acter used by Bartsch to define the subgenus Docomphalcfi'^ of the genus 

 Vitrinella. The present species combines this character with the spiral 

 sculpture of the genus Circulus instead of the smooth or axially marked 

 surface of the genus Vitrinella. It may be better to consider Docomphala 

 as a genus characterized by this distinctive sculpture in the umbilicus 

 and add the present species to the 2 California species described by 

 Bartsch. 



This species is named for the late Dr. Fred Baker, San Diego, 

 California. 



Circulus nicholsoni Strong & Hertlein, new species 

 Plate 22, Figs. 2, 3, 4 



Shell small, depressed, opaque white; nuclear whorls about 2, 

 smooth, merging without perceptible change into the following whorls; 

 postnuclear whorls about 3, upper surfaces evenly rounded, smooth ex- 

 cept for microscopic lines of growth, sutures appressed ; periphery of last 

 whorl with a slender, compressed keel; base evenly rounded between 

 the peripheral keel and the sharply angled edge of the open umbilicus, 

 sculptured with strong, curved lines of growth which rise to sharp, 

 microscopic points or serrations on the peripheral keel; umbilicus large, 



^'^ Docomphala Bartsch, Proc. U. S. Nat. Mus., vol. 32, February 8, 1907, 

 p. 169. "Type. — Vitrinella (Docomphala) stcarnsi." 



AN 



